Crews attempt to clear the collapsed equipment on May 22, 2018, where a worker is believed dead following a work-site incident at Phoenix Sky Harbor International Airport the day before.(Photo11: Phoenix Fire Department)

Crews spent more than 12 hours trying to clear the collapsed equipment but ceased operations around 11:45 p.m. Monday because of safety concerns, a Phoenix Fire Department official said.

Construction workers were able to safely remove the drill rig from the collapsed hole Tuesday, fire officials said.

Crews attempt to clear the collapsed equipment on May 22, 2018, where a worker is believed dead following a work-site incident at Phoenix Sky Harbor International Airport the day before.(Photo11: Phoenix Fire Department)

Removal involved using two large cranes. The rig was moved and stabilized to a safe location and both cranes were disassembled and moved because of safety concerns, fire officials said.

A vacuum truck was brought in to begin removing the dirt from the hole, which is 12 feet deep after dirt filled it after the rig collapse, fire officials said.

The missing drill-rig worker could be as deep as 30 feet, however, fire officials added.

The incident occurred just south of Sky Harbor Boulevard, near the West Economy parking lot and west of terminals 3 and 4. The site was on Sky Harbor property, as construction is being done for the PHX Sky Train.

The Sky Train guideway work — the track the cars ride on — is being overseen by contractor Hensel Phelps. The Colorado-based company also worked on earlier stages of Sky Train construction. It completed a $343 million project in 2012 that included the 120-foot elevated bridge over an airport taxiway and an underpass along 44th Street below the Union Pacific Railroad.

Hensel Phelps issued a statement to The Arizona Republic on Tuesday afternoon.

"Our focus right now is on supporting the recovery effort and on supporting the family," the statement said. "The identity of the missing worker is not being released out of respect for the family."

"Hensel Phelps places the highest value on safety and, upon completion of the recovery effort, this incident will be thoroughly investigated so we understand what led to this incident."

Crews attempt to clear the collapsed equipment on May 22, 2018, where a worker is believed dead following a work-site incident at Phoenix Sky Harbor International Airport the day before. Nick Oza/The Arizona Republic

Crews attempt to clear the collapsed equipment on May 22, 2018, where a worker is believed dead following a work-site incident at Phoenix Sky Harbor International Airport the day before. Nick Oza/The Republic

Crews attempt to clear the collapsed equipment on May 22, 2018, where a worker is believed dead following a work-site incident at Phoenix Sky Harbor International Airport the day before. Nick Oza/The Republic

Crews attempt to clear the collapsed equipment on May 22, 2018, where a worker is believed dead following a work-site incident at Phoenix Sky Harbor International Airport the day before. Nick Oza/The Republic

Crews attempt to clear the collapsed equipment on May 22, 2018, where a worker is believed dead following a work-site incident at Phoenix Sky Harbor International Airport the day before. Nick Oza/The Republic

Crews attempt to clear the collapsed equipment on May 22, 2018, where a worker is believed dead following a work-site incident at Phoenix Sky Harbor International Airport the day before. Nick Oza/The Republic

Crews attempt to clear the collapsed equipment on May 22, 2018, where a worker is believed dead following a work-site incident at Phoenix Sky Harbor International Airport the day before. Nick Oza/The Republic

Crews attempt to clear the collapsed equipment on May 22, 2018, where a worker is believed dead following a work-site incident at Phoenix Sky Harbor International Airport the day before. Nick Oza/TheRepublic

Crews attempt to clear the collapsed equipment on May 22, 2018, where a worker is believed dead following a work-site incident at Phoenix Sky Harbor International Airport the day before. Nick Oza/The Republic

Crews attempt to clear the collapsed equipment on May 22, 2018, where a worker is believed dead following a work-site incident at Phoenix Sky Harbor International Airport the day before. Nick Oza/The Republic

Investigators look down at a toppled drill rig that was being used in the construction of the Sky Train guideway system at Sky Harbor International Airport Monday, May 21, 2018, in Phoenix. The Phoenix fire department said one person is unaccounted for and their condition is unknown at this time due to the rig being on its side. Matt York/AP

Investigators look down at a toppled drill rig that was being used in the construction of the Sky Train guideway system at Sky Harbor International Airport Monday, May 21, 2018, in Phoenix. The Phoenix fire department said one person is unaccounted for and their condition is unknown at this time due to the rig being on its side. Matt York/AP

A plane takes off above a toppled drill rig that was being used in the construction of the Sky Train guideway system at Sky Harbor International Airport Monday, May 21, 2018, in Phoenix. The Phoenix fire department said one person is unaccounted for and their condition is unknown at this time due to the rig being on its side. Matt York/AP

Construction workers and airport personnel stand near a toppled drill rig that was being used in the construction of the Sky Train guideway system at Sky Harbor International Airport Monday, May 21, 2018, in Phoenix. The Phoenix fire department said one person is unaccounted for and their condition is unknown at this time due to the rig being on its side. Matt York/AP

A toppled drill rig that was being used in the construction of the Sky Train guideway system lies it's side at Sky Harbor International Airport Monday, May 21, 2018, in Phoenix. The Phoenix fire department said one person is unaccounted for and their condition is unknown at this time due to the rig being on its side. Matt York/AP

Crews attempt to clear the collapsed equipment on May 22, 2018, where a worker is believed dead following a work-site incident at Phoenix Sky Harbor International Airport the day before. Phoenix Fire Department

Crews attempt to clear the collapsed equipment on May 22, 2018, where a worker is believed dead following a work-site incident at Phoenix Sky Harbor International Airport the day before. Phoenix Fire Department

Crews attempt to clear the collapsed equipment on May 22, 2018, where a worker is believed dead following a work-site incident at Phoenix Sky Harbor International Airport the day before. Phoenix Fire Department

Crews attempt to clear the collapsed equipment on May 22, 2018, where a worker is believed dead following a work-site incident at Phoenix Sky Harbor International Airport the day before. Phoenix Fire Department

Crews attempt to clear the collapsed equipment on May 22, 2018, where a worker is believed dead following a work-site incident at Phoenix Sky Harbor International Airport the day before. Phoenix Fire Department

Praise for company

The city of Phoenix raved about the company's work, according to a testimonial on Hensel’s website.

Jay DeWitt, then-deputy director of the airport, said, “I would absolutely hire Hensel Phelps again. They were a terrific partner throughout the design phase and construction. Their estimates proved to be on target, their fee was fair, and they didn’t nickel and dime us with changes along the way. I would rate them outstanding, a perfect 10 with respect to the quality of their staff. They provided the best qualified and most professional staff (from top to bottom) of the many, many contractors I’ve worked with over the years."

The missing employee was working for Case Foundation, a subcontractor of Hensel Phelps, Sky Harbor spokeswoman Julie Rodriguez said.

"Our number 1 concern at this time is for the missing worker, the worker’s family and the safety of those who are working to find the missing employee,'' she said.

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Case, based in Illinois, calls itself a full-service deep foundation specialist. The company's parent company, the Keller Group, was a sponsor of the industry's Construction Safety Week earlier this month.

The Industrial Commission of Arizona, which enforces state laws relating to Arizona worker safety, is investigating the accident, spokesman Trevor Laky said, declining further comment.

Crews attempt to clear the collapsed equipment on May 22, 2018, where a worker is believed dead following a work-site incident at Phoenix Sky Harbor International Airport the day before.(Photo11: Phoenix Fire Department)